Of course, there's quite a few there I've not actually watched yet - I'd much sooner watch a good movie with company, but the roomie's tastes are generally quite different, leaning broadly more towards Hollywood action, such as 2 Fast 2 Furious (originally, my keyboard didn't pick up the first "s" in the title..) and Charlie's Angels 2, or comedies, including the works of Adam Sandler. Different strokes, and all that. I have succeeded in introducing him to MST3K, though - it's not something he calls out for more of, but we've enjoyed a few. (Still have to expose him to the end of Monster A Go-Go, though..)

Perhaps you've only caught the later MST3K shows that were created for the SciFi channel. I loved the show back when it was produced for Comedy Central but after the departure of Joel Hodgson (the original creator) and Trace Bealieu (Dr. Forrester and voice of Crow T. Robot, funniest guy on the show), it became unbearable for me to watch the in-between skits. The shows in question are easy to spot as they feature a female mad scientist and a guy in an ape suit.

The earlier shows aren't being shown anywhere as I can see, but a proper introduction to MST3K really should be something like Daddy-O, Catalina Caper, Cave Dwellers, or (my favorite) Mr. B Natural, a short educational film from the 50's that teaches high school students the healthy message that popularity is proportional to the size of your instrument, as demonstrated by an androgynously-dressed middle-aged woman who appears magically in young boy's bedrooms at night... It's worse than it sounds.

MST3K's humor is hit or miss as it tends to be obscure cultural references, Joel Hodgson's personal hostility toward anyone who ever beat him on Star Search, and geek humor (Amiga peripheral references in Godzilla vs. Gamera, I believe).